The invention relates to a method for the protection of a liquid stored in a container against the effects of atmospheric oxygen and to an apparatus for carrying out the method of the invention.
The invention is more particularly concerned with the protection of molten metal which would be liable to premature oxidation if atmospheric oxygen were to gain access to it.
There has already been a proposal to use a protective gas under pressure for the protection of molten metal against the atmospheric oxygen.
However this method involved the replenishment of protective gas to make good losses of the gas into the atmosphere and furthermore job environment as impaired Moreover any readjustment of the liquid level, for example that of molten metal, was complex owing to the compressibility of gases. A further disadvantage in connection with protective gas operations is that on actuation of the safety circuit all gage pressure in the machines and plant has to be let off (to comply with industrial safety regulations). This letting off of the gas under pressure may impair or completely override the protective effect of the gas. A rapid discharge of the pressure, as required by the regulations, also leads to an uncontrolled motion of the liquid and splashing. In those cases in which the liquid to be protected has to be held at a raised temperature, the protective gas tends to prevent the transmission of heat.